Patent GB-761032-A (GB)
Title: Process and apparatus for making solder terminals for electric lamps
IPC: H01J5/62
Filed: 1954-11-19
Abstract: 761,032. Making electric lamps ; forging ; shearing. BRITISH THOMSON-HOUSTON CO., Ltd. Nov. 19, 1954 [Nov. 19, 1953], No. 33611/54. Classes 83 (2) and 83 (4). [Also in Group XI] A lamp cap is provided with an end contact, or pair of contacts, each formed by a bead of solder located within a small depression or well provided in the surface of the insulating web at the end of the cap the solder bead being formed by threading a perforated slug of solder 16 or 17, Fig. 1b, over a projecting end of a leading-in wire 14 or 15, trimming off the excess length of wire projecting beyond the solder slug, and heating the slug to its melting point so that it is drawn into a generally spherical bead attached to the end of the leading-in wire, with part of the bead within the well and the remainder projecting above the surface of the web. Apparatus for carrying out the operations may be combined with an automatic lamp-finishing machine such as that described in Specification 247,923, [Class 83 (iv)], comprising a turret machine which indexes a series of lamp bulbs through successive work stations. In the example the operations of forming slugs of solder from a continuous length of solder wire and feeding them to the leading-in wires, close-trimming the leading-in wires, and melting the solder slugs to form contact beads, are performed at three successive work-stations A, B and C, Fig. 2 (not shown), adjacent to and outside the periphery of the turret. Each workholding head 23, Fig. 3, comprises a bracket 24 mounted on the edge of the turret 21 and provided with a vacuum cup 26 for holding the bulb 2 in place, and an apertured arm 25 for supporting the cap 5 in conjunction with an arm 27 which presses down on the cap to seat it firmly in the aperture of arm 25. The filament may be pre-focused accurately in known manner by operation of a raising and lowering wheel 29 and a pair of lateral shift wheels such as 30. In the case of a two-contact cap two solder-feeding units each similar to that shown in Fig. 3 are provided. Solder wire 32 is fed from a spool and over a pulley (not shown) to mechanism which flattens it to a fairly thick ribbon and perforates it at regular intervals, after which the ribbon is cut into successive slugs which are picked up and released over the upwardly projecting ends of the leading-in wires of the lamp. The mechanism comprises a main slide 34 which is reciprocated horizontally in a channel within a standard 35, the front part of the slide 34 providing a mounting for a block 37 housing a vertically reciprocable slide bar 36. A hollow spindle 38 passing through the slide bar 36 is adjustable relative to the latter by a nut 39 on the screw-threaded upper end of the spindle, and the lower end of the spindle, which is machined to a substantially rectangular shape, has a downwardly projecting knife-edge cutter 42 at its rear portion. A pick-up pin 43 fastened to a slider 44 enclosed within the bore of the spindle 38 projects beyond the lower end of the latter, the slider and pick-up pin being urged downwardly by a spring 45 within the bore. The extent of projection of the pin 43 is limited by a stop-pin 46 mounted transversely within the slider 44 and extending laterally through vertical slots in the wall of spindle 38. The cutter 42 and pick-up pin 43 are carried backwards and forwards by the slide 34, and at the rearward limit of the stroke they are reciprocated downward, so that the cutter cuts off a solder slug and the pick-up pin 43 lifts it. At the forward limit of the stroke the slug is deposited to the upper end of the leading-in wire and on to the bottom of the lamp cap and the slide is then lifted to clear the cap and its holder. The horizontal reciprocation of slide 34 is effected by a vertically reciprocating rod 48 which is pivoted to a bell-crank 49 and rocks it about a fixed pivot 52 in opposition to a spring 53, the upper end of the bell-crank being connected by a link 51 to the slide. The operating rod 48 moves in synchronism with the camshaft of the machine. Vertical reciprocation of the slide bar 36 is effected by a rocking-arm 59 mounted on a pivot 71 on the standard 35 and provided with an elongated slot 72 at its outer end to receive a lateral pin 73 on the slide bar 36. The other end of the arm 59 is connected by a pair of linked universal joints 58, 56 to a vertical slide rod 55, the lower end of which is connected releasably to a vertically reciprocating operating rod 54 by a transverse pin 62 in the former engaging within a lateral slot 61 in the latter. Normally the pin 62 is maintained within the slot 61 by a spring-pressed push-rod 63. If, however, a head 23 not containing a lamp is presented at station A, the spring-loaded arm 27 does not occupy the position shown in Fig. 3, but is tilted inwardly, carrying with it a roller 67 mounted upon it. This results in closure of a safety switch 69 controlling a solenoid 66 with an armature 65 which is projected to disengage the coupled members 54, 55. Solder feedings. The solder wire 32 is fed into the mechanism through an anti-slip-back device 74 at the rear of the standard 35 and thence through a feed block 75, Fig. 4, containing a compressed-air actuated piston 76 the face of which is serrated at 77 to grip the solder wire. The feed-block 75 is mounted on a horitontal rod 78, Fig. 3, which is reciprocated longitudinally backwards and forwards a distance equal to the required length of a solder slug, the rod 78 being provided with a collar which is engaged by the lower arm of a lever 83 pivoted at 84 on the fixed standard 35, whilst the longer arm of the lever is connected by a slotted link 81 to the main reciprocating slide 34. On the forward movement of the feed block 75 air is admitted to the piston 76, causing the serrated face 77 to grip the solder wire and carry it forward. Air is cut off during the return movement, and slip-back of the solder wire is prevented by the pressure of the sharpened forward end of a spring-biased lever 91. Solder flattening. The solder wire passes over an anvil plate 94, Fig. 4, where it is flattened to a moderately thick ribbon by a hammer face 95 on a vertically reciprocable block 96 operated by a piston in an air cylinder 98. After flattening, the ribbon enters a passage through a guide block 104 where a pin on a punch 105 mounted on the reciprocating block 96 moves through a hole in the guide block and pierces a hole 106 in the ribbon. Shearing into slugs. The perforated solder ribbon is next sheared into separate slugs by the cutter 42 carried by the vertical slide bar 36 operating at the rearward position of the main slide 34, the pick-up pin 43 being then aligned with a hole in the ribbon, so that it enters the hole just before the cutter shears off the slug, the shape of the pick-up pin being such that, assisted by the slight crushing of the slug during severing, the slug stays on the pin when the slide bar 36 is raised and the main slide 34 moves forward. The slug is next lowered into register with the end of a leading- in wire 14 of a lamp 1 indexed into station A, the accurate positioning of the wire being ensured by a device comprising a pair of mating V-notched combing members 113, 114, Fig. 4, supported on the ends of laterally slidable bars 115, 116. The combing members are normally spaced apart by a wedge 117 mounted on the upper end of a vertically reciprocable rod 118 and normally entered between a pair of rollers 119, 121 on the respective ends of the bars 115, 116. When the pick-up pin 43 reaches a point immediately above the leading- in wire 14 its further descent is prevented by a stripping plate 125, but-the slide bar 36 continues to move downward a slight amount so that the rectangular end portion 41 presses the solder plug off the end of the pick-up pin. The slug is thus threaded on to the leading-in wire, and seats itself upon the insulating web of the lamp cap, after which the positioning combs are withdrawn. The lamp is indexed to station B, Fig. 2 (not shown), with the slugs located as shown in Fig. 1b and necessitating the trimming of the leading-in wires 14, 15 by cutters 126, 127, Fig. 5, fastened on the ends of oppositely reciprocating slides 128, 129 located within a block 131 and provided with rack-teeth portions 132, 133 meshing with a common pinion 134. The block 131 is supported on a vertical slidable bar 136 mounted in a bracket 137, and the lower slide-bar which supports cutter 127 is actuated directly by an air piston coupled to it by a link 139. The pinion 134 causes the cutters to close together in unison, a preliminary closing being effected by a bell-crank 141 which has one arm engaging a roller 144 on the slide 129 and the other engaging a roller 143 on the fixed bracket 137. After the trimming of the wires 14, 15 the lamp is indexed to station C, where the solder slugs are melted by flames from gas jets 145, 146, Fig. 2 (not shown), the surface tension of the molten solder being sufficient to draw it into a bead. with a part projecting above the surface of the web. Specification 524,414, [Group XI], also is referred to.